Method for manufacturing ribbon cable and transposed cable

ABSTRACT

Methods and apparatus for manufacturing an improved ribbon cable comprising a plurality of insulated wires juxtaposed in fixed relationship to each other and an improved transposed cable in which each conductor of the cable of the invention is in the form of a continuous helix. The electromagnetic device of the invention has the ribbon cable of the invention as its magnetic windings.

RELATED APPLICATION

This application is a divisional application of Ser. No. 634,041, filedJul. 24, 1984 and now U.S. Pat. No. 4,650,924.

BACKGROUND OF THE INVENTION

The present invention relates to electrical cable and particularly toribbon cables in which insulated conductors are juxtaposed, in a fixedrelationship to each other, and more particularly, to transposed ribboncables in which the conductors are in the shape of juxtaposed laterallyflattened helices, methods and apparatus for manufacturing the same, andelectromagnetic devices having ribbon cable as its magnetic windings.

Electrical cables in a variety of configurations have been available foran extended period of time. One of those varieties is ribbon cable. Inribbon cable, a plurality of conductors are disposed side by side toyield a cable with a roughly rectangular cross section as opposed to theround cross section of ordinary cables. The rectangular cross sectionpermits use of the ribbon cable in applications where one or twodimensions are constrained.

Ribbon cables also provide improved field or armature and statorwindings in a number of electromagnetic devices such as motors andgenerators and transformers. Ribbon cables in many applications providefor increased ease of assembly and improved efficiency. In someelectromagnetic devices, eddy current losses can be reduced drasticallyby use of transposed ribbon cable. In other electromagnetic device,these eddy current losses can be balanced against other losses toproduce an electromagnetic device having a greatly improved efficiency.

In transformer design, greater energy efficiency is achieved by usingribbon cable. Load losses can be reduced by using transposed ribboncable. Similar benefits and similar energy efficiencies can be achievedin rotating electromechanical device design using ribbon cables andtransposed ribbon cables.

Further, transposed cables heretofore have been limited as to the numberof conductors in the cable. This limitation is the result ofconventional methods and apparatus for manufacturing transposed cable.No such limitation exists for the ribbon cable of the invention.

It is therefore highly desirable to provide an improved ribbon cable, animproved ribbon cable that has a flattened generally rectangular crosssection, an improved ribbon cable in which insulated conductors arejuxtaposed in fixed relation to each other, an improved ribbon cable inwhich the conductors are at an angle to the longest dimension of thewire cable, an improved transposed ribbon cable, improved methods andapparatus for producing such cables, and an improved electromagneticdevice using the ribbon cable of the invention as its magnetic windings.

SUMMARY OF THE INVENTION

It is an object of this invention to provide methods and apparatus formanufacturing an improved ribbon cable.

Another object of the invention is to provide a method and apparatus forproducing an improved ribbon cable in which the insulated conductors arejuxtaposed in fixed relation to each other.

Another object of the invention is to provide a method and apparatus forproducing cables in which the conductors are disposed at an angle to thelongitudinal dimension of the cable and define a plurality of juxtaposedlaterally flattened helices.

Yet another object of the invention is to provide methods and apparatusfor producing cables in which there is no limitation as to the number ofconductors.

A further object of the invention to provide methods and apparatus forproducing cables which meets all the above desired features.

Still a further object of this invention is to provide improvedelectromagnetic windings having reduced eddy current losses and/orimproved overall energy efficiencies.

Finally, it is an object of the invention to provide an improvedelectromagnetic device which has the ribbon cable of the invention withone or more of the above desired features as its magnetic windings.

In the broader aspects of the invention there is provided methods andapparatus for manufacturing an improved ribbon cable comprising aplurality of insulated wires juxtaposed in fixed relationship to eachother and an improved transposed cable in which each conductor of thecable of the invention is in the form of a continuous helix. Theelectromagnetic device of the invention has the ribbon cable of theinvention as its magnetic windings.

Yet another object of the invention is to provide an improved transposedribbon cable in which there is no limitation as to the number ofconductors and methods and apparatus for producing such cables.

A further object of the invention to provide an improved ribbon cablewhich meets all the above desired features and methods and apparatus forproducing such cables.

Still a further object of this invention is to provide improvedelectromagnetic windings having reduced eddy current losses and/orimproved overall energy efficiencies.

Finally, it is an object of the invention to provide an improvedelectromagnetic device which has the ribbon cable of the invention withone or more of the above desired features as its magnetic windings.

In the broader aspects of the invention there is provided an improvedribbon cable comprising a plurality of insulated wires juxtaposed infixed relationship to each other. An improved transposed cable in whicheach conductor of the cable of the invention is in the form of acontinuous helix. An electromagnetic device having the ribbon of theinvention as its magnetic windings, and methods and apparatus formanufacturing both the ribbon cable and the transposed cable of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

The above mentioned and other features and objects of this invention andthe manner of obtaining them will become more apparent and the inventionitself will be better understood by reference to the followingdescription of an embodiment of the invention taken in conjunction withthe accompanying drawing wherein:

FIG. 1 is a perspective view of the longitudinal ribbon cable of theinvention;

FIG. 2 is a perspective view of the transposed ribbon cable of theinvention;

FIG. 3 is a top plan view of the ribbon cable of the invention in whicha single wire of the embodiment of FIG. 2 is emphasized for clarity;

FIG. 4 is a schematic diagram of a portion of the apparatus of theinvention for the production of the ribbon cables of FIGS. 1, 2 and 3;

FIG. 5 is a schematic diagram of the remaining portion of the apparatusof the invention;

FIG. 6 is a schematic diagram of part of the apparatus of FIG. 5;

FIG. 7 is a perspective view of an armature having the ribbon cable ofthe invention as its magnetic windings; and

FIG. 8 is a perspective view of a stator having the ribbon cable of theinvention as its magnetic windings.

DESCRIPTION OF A SPECIFIC EMBODIMENT

The ribbon cable 110 is shown in FIG. 1 to comprise a plurality ofjuxtaposed conductors 18 having superimposed thereon a flexible,continuous, and concentric coat of insulating material 19 and are heldin fixed relationship to each other by a bonding material 20. In aspecific embodiment, bonding material 20 has sufficient insulatingproperties for the requirements of a particular use and functions as thebase insulation for conductors 18. In an alternative specificembodiment, ribbon cable 110 would include a continuous and concentriccoat of flexible bonding material 21 superimposed on insulating coat 19.

Ribbon cable 110 of the invention has a generally rectangular crosssection with an upper surface 12, a lower surface 14 and two edges 17.Upper surface 12 and the lower surface 14 are generally parallel androughly planar to each other with deviations from that shape generallydue to the cross sectional shape of the conductors 18. In a specificembodiment, rectangular cross section conductors 18 are used and theplanarity of the surfaces 12, 14 is better that than shown in FIG. 1.

In the transposed ribbon cable 210 of the invention, conductors 18 areall in the shape of laterally flattened helicies with upper segments 22and lower segments 24 being coplanar with each other at an oblique angleto the longest dimension of the cable 210 as shown in FIGS. 2 and 3. Theupper and lower segments 22, 24 of each conductor 18 are sequentiallytransposed throughout the length of the cable 210 and conductors 18 aregenerally coplanar and generally parallel to the longest dimension andlongitudinal axis of the ribbon cable 110.

This relationship may be described mathematically by the followingformulas in which "a" equals the acute angle 30 between the upper andlower segments 22, 24 of the helicies and the longest dimension of thetransposed ribbon cable 210, "N" equals the number of conductors 18 inthe transposed ribbon cable 110, "d" equals the nominal outside diameterof conductors 18, "W" equals the cable width of the transposed ribboncable 210 perpendicular to its longest dimension, "P" equals the pitchof the transposed ribbon cable 210, i.e. the distance between successiveupper segments 22 or lower segments 24 of conductor 18 in a directionparallel to the longest dimension of the transposed ribbon cable 210."CL" equals the length of the transposed ribbon cable 210, and "SL"equals the strand length or the length of a conductor 18 in a transposedribbon cable 210 of length "CL": ##EQU1## Angle 30 in all embodimentsranges from slightly greater than 0 to slightly less than 90 degrees.

In the transposed ribbon cable 210 of the invention of FIGS. 2 and 3,the upper and lower segments 22, 24 define upper and lower layers 26 and28, respectively. Upper layer 26 and the lower layer 28 are bondedtogether by bonding material 32. In a specific embodiment, bondingmaterial 32 may be the same as bonding material 20. Conductors 18 in theupper segments 22 and the lower segments 24 of the transposed ribboncable 210 are angularly disposed to the longest dimension of the cable210 and at an adjacent angle to the segments of the opposite layer 22 or24.

In a specific embodiment of the transposed ribbon cable 210 of theinvention as shown in FIGS. 2 and 3, 600 conductors 18 of 0.020 inchbare copper are used, each conductor 18 has superimposed thereon apolyvinyl formal enamel coating and is bonded to adjacent conductors 18with a polyvinyl butyral enamel. The 300 upper segments 22 together withtheir bonding material 20 form the upper layer 26 and the 300 lowersegments 24 together with their bonding material 20 form the lower layer28. Layers 26 and 28 are bonded together with their bonding material 32.

In other embodiments, the number of conductors 18 may vary from a few toseveral thousand. An unlimited number of conductors 18 may be positionedin one or more ribbons of generally coplanar conductors 18 as shown inFIG. 1 and bonded together to be used as ribbon cable 110 or folded asillustrated in FIG. 2 and used as transposed ribbon cable 210.

One method of the invention for making the transposed ribbon cable 210of the invention comprises the steps of insulating one or moreconductors 18 using conventional magnet wire enamel solution coatingmethods or the methods generally disclosed in U.S. Pat. No. 4391848,wrapping one or more conductors 18 obliquely around a laterallyflattened mandrel 34 at a chosen constant angle to achieve the desiredpitch and removing those conductors from the mandrel 34 as theconductors 18 are wrapped to form a plurality of juxtaposed laterallyflattened helices having upper segments 22 and lower segments 24,applying bonding agent 36 between helices and the upper and lowersegments 22, 24, as segments 22, 24 are being formed or after segments22, 24 are formed by impregnation techniques, and severing the ribboncable formed thereby at opposite ends to expose a plurality of conductorends.

In a specific embodiment, the bonding agent 36 may be, for example, abonding material 32 or an activator (such as heat or a solvent) of aB-stage bonding material 20 or 32 previously applied to the conductors18.

In some of the cable configurations of the invention, the insulatedconductors 18 are magnet wire and are in accordance with ANSI/NEMAMW-1000 Standards.

In some of the cable configurations of the invention, less build andlower dielectric values than required by the ANSI/NEMA MW1000 Standardsare acceptable. The lower limits of build and dielectric value aredetermined by the anticipated turn to turn voltage differentials of thespecific contemplated application.

The wrapped conductors 18 are then compressed both in a directionstransverse of the cable 210 in which the upper segments 22 and lowersegments 24 are compressed together and at right angles thereto axiallyof cable 210 so as to form a plurality of juxtaposed laterally flattenedhelices. The edges 16 of the transposed ribbon cable 210 of theinvention may be then rolled to result in a compact generallyrectangular cross-sectional cable with a roughly planar upper layer 26,a roughly planar lower layer 28 and two edges 16. This results in acompact generally rectangular cross-sectional shape with a roughlyplanar upper layer 26, a roughly planar lower layer 28 and two edges 16.

In a specific embodiment, the compressing step is performedsimultaneously with the wrapping and removing steps by differentiallytransporting conductors 18 in the direction of transport as thewrapping, removing and bonding steps are performed.

The resulting cable is an integral cable with the conductors bondedtogether with the bonding material surrounding each conductor anddefining with the conductors the boundaries of the cable. The ribboncable 210 can be wrapped with exterior insulation material eitherspirally or longitudinally and spooled for shipping as desired.

In all embodiments of the method above described, the source of theconductors 18 for the wrapping step are a plurality of wire spoolsmounted for rotation on a plurality of spindles. To achieve the wrappingstep, either the spools must be rotated around the mandrel 34, or themandrel 34 must be rotated around the spools. The number of conductorsused in the method may determine the apparatus used in performing themethod and the number of steps performed at a single work station.

In another method of the invention for producing transposed ribbon cable210, the insulated conductors 18 are first formed into the longitudinalribbon cable 110 of FIG. 1. The method of making the ribbon cable 110includes the step of insulating a plurality of conductors 18 usingconventional magnet wire in enamel coating methods or those methodsdisclosed wrapping or U.S. Pat. No. 4391848, paying out as manyinsulated conductors 18 as are required, simultaneously, and guiding theconductors into the form of a ribbon 38 wherein the longitudinal axis ofeach conductor is parallel to the axes of the others and define a singleplane, and the exterior surfaces of each conductor are contiguous toadjacent conductors.

The conductors 18 are then bonded together to form the cable 110. Thebonding step can be performed either by utilizing a B-stage bondingmaterial superimposed on the insulated conductors 18 subsequently to theinsulating step and then performing the bonding step by activating thebonding material during the bonding step. Alternatively, bondingmaterial may be applied to the contiguous and parallel conductors of theribbon 38 during the bonding step and after the performance of theguiding step. Preferably, care should be taken to impregnate or fill allof the intersticies between the conductors 18. This can be achieved byutilizing modified vacuum impregnation techniques or pressurized bondingtechniques, if desired.

The bonding step continues by wiping the excess of the bonding materialfrom the ribbon and hardening the bonding material so as to form cable110. During the wiping and hardening steps, the respective conductors 18are maintained in the same position as afore-described in the guidingstep and the upper surface 12, the lower surface 14 and the two edges 17are formed.

In a specific embodiment, conductors 18 may be insulated and formedtogether as a ribbon 38 and bonded together with a bonding materialextruded onto the conductors by transporting the conductors through aheated die with an opening slightly larger than the dimensions of theribbon, and quenched.

In manufacturing transposed ribbon cable 210, the ribbon cable 110 isfolded over itself, repeatedly, to produce ribbon cable 210 as shown inFIGS. 2 and 3. The folding of the cable 110 to form the transposed cable210 forms each of the conductors of the cable into a plurality ofjuxtaposed laterally flattened helices having upper segments 22 andlower segments 24. Each fold positions the conductors 18 of the foldedportion angularly with respect to the conductors of the precedingportion and with the axis of the finished cable 210.

The folding step comprises the steps of paying out the ribbon 110 at anangle to the desired axis of the transposed ribbon cable 210 a measuredamount, folding the ribbon cable 110 against a first straight edge of aflat folding mandrel rotating the folded cable in the direction of thefold and folding the ribbon cable 110 about a second straight edge ofthe folding mandrel. The first and second straight edges of the mandrelare parallel to each other, and spaced from each other the desired cablewidth. Paying out cable 110 a second measured amount to move the secondfold so as to be coincident with the first straight edge of the mandrel,and folding the cable 110 a third time. Cable 110 is repeatedly paid outand folded in this manner.

Simultaneously with the folding step, bonding material 32 may bepositioned between the folded portions. Subsequently thereto, the foldedportions may be compressed and bonded together to form the bondedtransposed ribbon cable 210. Again the bonding step, in specificembodiments, may include the aforementioned application of solvent orheat, or the use of vacuum or pressure impregnating techniques orB-stage bonding materials. The transposed ribbon cable formed by thismethod may then be wrapped with exterior insulation material, eitherspirally or longitudinally, and spooled for shipment.

In all of the aforementioned folding and wrapping steps, the folding andwrapping stations may be stationary and the insulated conductor 18 andcable 110 pay-off reels rotated around the folding mandrel; or in thealternative, the folding and wrapping stations may be rotated aboutpay-off reels from which ribbon cable 110 or conductors 18 are suppliedto the folding or wrapping stations as afore-described. The specificapparatus used in the performance of the method of the invention will bedescribed in more detail hereinafter.

Depending upon the bonding material utilized, ovens, heated dies or thelike may be used in the bonding step. Conventional bonding materials mayeither be thermoplastic and thereby softened and made flowable by theapplication of heat or may be softened by the application of solventslater to be driven off by the application of heat. Whenever heat isutilized in the bonding steps afore-described, a water quench or aircooling may be necessary.

The apparatus of the invention is illustrated in FIGS. 4 through 6. Inmaking the cable 110, the conductors are first insulated asabove-described, and may be spooled for handling. B-stage bondingmaterials may be superposed on the insulated conductors if desired inaccordance with the afore-described insulating methods. Conductors 18are transported then from conductor supplies or spools 42 or directlythrough a guide 44 to form the conductors into a ribbon 38 of parallelcoplanar wires. Suitable bonding material 20 may be applied to theribbon 38 by the applicator 46. The applicator 46 may take several formsin different specific embodiments. The applicator 46 in all embodimentsmust hold the conductors 18 in the form of ribbon 38 throughout thebonding step and until the bonding material is hardened and the ribbon38 is bonded together as in a single piece. In specific embodiments, theapplicator 46 may be a heated extrusion die in which the die opening isgeometrically similar and only slightly different from the desiredcross-sectional dimensions of the cable 110. In accordance withconventional extrusion technology, the die opening may be either largeror smaller than the desired dimensions of the cable 110.

In another specific embodiment, the applicator 46 may be a heatedchannel also having a channel opening with a cross-sectional shapegeometrically similar but slightly larger than the desired dimensions ofthe cable 110. In this embodiment, the channel merely holds the ribbon38 of parallel co-planar wires in the shape desired and forms theexterior dimensions of the cable 110 when the bonding material hardens.

In other specific embodiments, the parallel co-planar conductors 18 maybe held in the form of ribbon 38 by oppositely disposed side portionsand the opposite edges 17 of the ribbon 110 are formed by the continualwiping of the ribbon on the oppositely disposed side portions, whereasthe upper surface 12 and the lower surface 14 are formed by wipers whichcontinually wipe the excess bonding material from the ribbon 38.

Bonding material 20 is activated by passing the ribbon through an oven48, or alternatively by exposing the bonding material 20 to a solventtherefore. The bonding material is softened into a flowable form in bothembodiments, and in both embodiments oven 48 is required. Oven 48softens the bonding material 20 in the former case, and drives off thesolvent in the later case. Heat may also be used to assist a solvent insoftening bonding material 20. In all cases, oven 48 may additionallycure either the insulation or bonding material, or both.

The bonded ribbon cable 110 is then transported through pressure rollers50. In the specific embodiment illustrated, additional bonding material20 is applied to the ribbon cable 110 by means of extruder 52 and ribboncable 110 is transported through a heated die 40 and a quenching unit54. Thus two specific embodiments of the apparatus of applying bondingmaterial 20 to the ribbon 38 are shown. In other specific embodiments,only a single embodiment or a combination of the two differentembodiments may be used. The excess bonding material is removed by apressurized air at air wipe 56.

The finished longitudinal ribbon cable 110 is either wound onto a takeup reel 58 which also provides the motive power for the transportationor is input into the remaining portion of the apparatus by which thetransposed ribbon cable 210 of the invention is manufactured. Thisremaining portion of the apparatus of the invention for the productionof tranposed ribbon cable 210 is illustrated in FIG. 5 and 6.

Referring to FIGS. 5 and 6, a wire supply 60 delivers either the ribboncable 110 or one or more conductors 18, as the case may be, to a foldingmandrel 34 to form a plurality of laterally flattened continuous helicesdefined by each conductor 18. The wrapping is performed by changing therelative position of the mandrel 34 and the wire supply 60 in a rotationabout the axis 62 and folding the conductors 18 or cable 110 about theouter straight edges of mandrel 34. The ribbon cable 110 may be theribbon cable 110 disclosed herein or the ribbon cable disclosed in U.S.patent application Ser. No. 634,040 entitled "Ribbon Cable" by John C.Kauffman filed Jul. 24, 1984 now U.S. Pat. No. 4,692,566 and U.S. patentapplication Ser. No. 634,042 entitled "A Ribbon Cable, A TransposedRibbon Cable And A Method And Apparatus For Manufacturing TransposedRibbon Cable" by Jessie H. Coon filed Jul. 24, 1984, now U.S. Pat. No.4,658,090, both of which are assigned to Phelps Dodge Industries, Inc.and are incorporated herein by reference. The relative rotation of thewire supply 60 around the axis 62 and the mandrel 34 may be achieved byeither rotating the wire supply 60 around the axis 62 and maintainingthe mandrel 34 stationary or by rotating mandrel assembly 64 about theaxis 62 and maintaining the wire supply 60 stationary. Conventionalmachine elements may be used to provide these motions.

The conductor supply 60 at all times pays out conductor 18 or cable 110at an oblique angle to the axis 62 of the mandrel 34 as the relativemovement occurs. That angle 30 determines the ratio of the cable widthto the cable pitch. As the cable 210 is wrapped, bonding agentapplicator 76 applies bonding material 20 between the layers 26, 28, asdesired. The mandrel 34 is longitudinally tapered in the direction ofcable movement as indicated by the arrow in FIGS. 5 and 6. This taperingof mandrel 34 allows the cable 110 and conductors 18 to be properlyfolded and the folded cable 210 to be easily removed from mandrel 34.

In one embodiment, the lateral dimension of mandrel 34 can beselectively varied. This permits transposed ribbon cable 210 ofdifferent cable widths to be produced on the same mandrel 34. In thatembodiment, mandrel 34 has a central member 82 perpendicular to the axis62 and two spaced members 84 adjustably joined to central member 82 at avariety of equidistant points away from the axis 62. Members 84 eitherhave slightly tapered outer edges or are secured to central member 82 atan angle to provide the desired taper.

The apparatus of the specific embodiment illustrated uses a caterpillar68 to both move and compress the wrapped cable 210 after cable 210 ismoved off the mandrel 34. Caterpillar 68 comprises a series of opposedrollers 70 interconnected on each side by belts 72 through which cable210 is fed. The opposed rollers 70 are spaced apart at a distancerequired to compress the cable 210. In a specific embodiment, therollers 70 are arranged in order of increasing diameter along thedirection of travel of cable 210 and all of the rollers 70 on one sideof cable 210 are rotated simultaneously by the movement of cable 210.The differential of the sizes of the rollers 70 causes the movement ofcable 210 to be slowed as the cable 210 proceeds in the direction oftravel. This causes the conductors 18 of cable 210 to simultaneouslybunch up and to compress both in the direction of transport and indirections perpendicular to the direction of transport.

The speed of movement of cable 210 relative to the wrapping of the cable110 or conductors 18 around mandrel 34 determines the pitch of thetransposed ribbon cable 210 produced. The edges 16 of the wrapped wires18 are then formed by rollers 74.

The finished cable 210 can then be wrapped with insulating material 78delivered by material supply 80, if desired. The wrapping shown isspiral wrapping. Longitudinal wrapping as disclosed in U.S. Pat. No.3,842,192 may be preferred in some applications. Rollers 82 secure theinsulating material, and may be heated if desired. The finishedtransposed cable 210 is transported onto a take up reel 66 for shipping.

Bonding materials 20 and 32 have been disclosed hereinabove to beactivated by the application of heat, or by the application of solvents,or both. In the apparatus illustrated in FIGS. 5 and 6, heat is appliedby pre-heating the bonding material prior to application, heating themandrel 34, or heating the rollers 70 and 82. Alternatively, an oven anda quench, such as oven 48 and quench 54, can be positioned on oppositesides of the caterpillar 68 and rollers 74. Sufficient solvent usuallycan be applied with the bonding material by applicator 76 to reactivateany bonding material on the conductors 18 or the cable 110. Additionalsolvent, however, can be supplied as desired.

In other specific embodiments, an essentially continuous and concentriccoat of flexible bonding material is superimposed on the coat ofinsulating material 19 by the same methods as above disclosed.

Generally, no additional bonding material need be applied to adhere thewrapped insulating material 78 to the cable 210. Generally, the wrappingof insulating material 78 occurs while the bonding material is stillactivated and the bonding material adheres the wrapping 78 to theconductor 210. However, additional activation may be supplied byapplying heat or solvent, as desired, prior to the rollers 82.

In specific embodiments of the invention, conductors 18 may be eithercopper or aluminum conductors.

Referring now to FIGS. 7 and 8, specific embodiments of the improvedelectromagnetic devices of the invention is shown. Shown in FIG. 8 is anarmature having as its magnetic windings the ribbon cable 110 or 210.FIG. 9 shows a stator having as its magnetic windings the ribbon cable110 or 210 as its magnetic windings. In both instances, the improvedelectromagnetic devices have improved windings in which energy lossesare greatly reduced. Both the armature and stator as afore-describedresult in an improved electromagnetic device having a greatly improvedefficiency.

While a specific embodiment of the invention has been shown anddescribed herein for purposes of illustration, it is desired that theprotection afforded by any patent which may issue upon this applicationnot be limited strictly to the disclosed embodiment; but that it extendto all structures and arrangements and methods and articles whichcontain the essence of the invention and which fall within the scope ofthe claims which are appended herein.

What is claimed is:
 1. A method of making ribbon cable comprising thesteps of: providing one or more elongated conductors, superimposing oneach of said conductors a relatively thin, flexible and generallycontinuous and concentric coating of insulating material, wrapping eachof said conductors obliquely around an elongated mandrel of sheetmaterial having opposed spaced apart edges and generally flat andparallel surfaces to form each conductor into a helix, said conductorsdefining an angle with the axis of said mandrel, compressing saidhelices together axially of said mandrel, said helices being side byside, flattening said helices transversely of said mandrel axis andgenerally perpendicularly of said mandrel surfaces, bonding said helicestogether in the compressed and flattened state thereof, thereby formingan integral ribbon of juxtaposed laterally flattened helices, andsevering said ribbon at opposite ends transversely of said mandrel axisthereby to expose a plurality of conductor ends.
 2. The method of claim1 wherein each of said conductors forming said helices has uppersegments and lower segments, said upper segments being oblique to thelongest dimension of said ribbon and at adjacent angles to said lowersegments of said conductors, and said lower segments of said conductorsare oblique to said longest dimension of said ribbon and at adjacentangles to said upper segments of said conductors.
 3. The method of claim1 wherein said ribbon comprises a plurality of conductors, the width ofsaid ribbon and the direction of said flattening is essentially equal tothe number of conductors in said plurality multiplied by the outsidediameter of said conductors and divided by twice the cosine of the acuteangle between said conductors of said laterally flattened helices andthe longitudinal axis of said ribbon.
 4. A method of making ribbon cablecomprising: providing a plurality of elongated first conductors,superimposing on each of said first conductors a relatively thin,flexible and generally continuous and concentric coating of insulatingmaterial, placing said first conductors side by side with the axis ofsaid first conductors extending parallel to each other and defining acommon plane with the insulating coating of adjacent conductors beingcontiguous, providing a plurality of elongated second conductors,superimposing on each of said second conductors a relatively thin,flexible and generally continuous and concentric coating of insulatingmaterial, placing said second conductors side by side with the axis ofsaid second conductors extending parallel to each other and defining acommon plane with the insulating coating of adjacent conductors beingcontiguous, placing said first conductors and second conductors side byside, bonding said first conductors together and bonding said secondconductors together to form an integral ribbon cable having generallystraight longitudinal boundaries, generally flat upper and lowersurfaces and a generally rectangular cross section essentially, definedby said first and second conductors.
 5. The method of claims 1 furthercomprising: folding said ribbon cable against a first straight edgedefining a first fold, said first fold being angularly disposed to theaxis of said conductors, said axis of said ribbon cable before and aftersaid first fold defining an angle between 0° and 90° with the axis ofsaid cable, paying out an amount of said ribbon cable equal to the widthof said ribbon cable divided by the sine of said angle, folding saidribbon cable against a second straight edge defining a second fold, saidsecond fold being angularly disposed to the axis of said conductors,said axis of said ribbon cable before and after said second folddefining the same angle as before and after said first fold, positioningsaid folds to define the longitudinal boundaries of a folded ribboncable, and repeating said paying out and said second folding and saidpositioning steps over and over again until a desired length of cable isformed, said straight edges being parallel and spaced apart a distanceequal to the desired width of the cable, and severing said folded cableat opposite ends transversely thereof to expose a plurality ofconductors.
 6. A method of making ribbon cable comprising: providing aplurality of elongated conductors, superimposing on each of saidconductors a relatively thin, flexible and generally continuous andconcentric coating of insulating material, placing said conductors sideby side with the axis of said conductors extending parallel to eachother and defining a common plane with the insulating coating ofadjacent conductors being contiguous, bonding said conductors togetherto form an integral ribbon cable having generally straight longitudinalboundaries, generally flat upper and lower surfaces and a generallyrectangular cross section essentally defined by said conductors, foldingsaid ribbon cable against a first straight edge defining a first fold,said first fold being angularly disposed to the axis of said conductors,said axis of said ribbon cable before and after said first fold definingan angle between 0° and 90° with the axis of said cable, paying out anamount of said ribbon cable equal to the width of said ribbon cabledivided by the sine of said angle, folding said ribbon cable against asecond straight edge defining a second fold, said second fold beingangularly disposed to the axis of said conductors, said axis of saidribbon cable before and after said first fold, positioning said folds todefine the longitudinal boundaries of a folded ribbon cable, andrepeating said paying out and said second folding and said positioningsteps over and over again until a desired length of cable is formed,said straight edges being parallel and spaced apart a distance equal tothe desired width of the cable, and severing said folded cable atopposite ends transversely thereof to expose a plurality of conductors.7. The method of claims 1, 4, 5 or 6 wherein said conductor layers arebonded together.
 8. The method of claims 1, 4, 5 or 6 wherein saidcoating of insulation material is in accordance with ANSI/NEMA MW1000Standards excepting the dimensional and dielectric standards, saiddimensional and dielectric standards being equal to ANSI/NEMA MW1000Standards or less.
 9. The method of claims 1, 4, 5 or 6 wherein saidconductors are chosen from the group consisting of aluminum and copperconductors.
 10. The method of claims 1, 4, 5 or 6 wherein saidconductors are provided in a number greater than thirty-one.
 11. Themethod of claims 1, 4, 5 or 6 further comprising the step ofsuperimposing an essentially continuous and concentric coating offlexible bonding material on said coating of insulating material. 12.The method of claims 1, 4, 5 or 6 further comprising the steps ofplacing bonding material in the interstices between said conductors,said bonding material generally defining the exterior configuration ofsaid ribbon cable with said conductors.
 13. The method of claims 1, 4, 5or 6 wherein said conductors are chosen from the group consisting ofaluminum and copper conductors, and said bonding material is the samematerial as said insulation material.
 14. The method of claims 1, 4, 5or 6 wherein said conductors are provided in a number greater thanthirty-one and said bonding material is the same material as saidinsulation material.
 15. The method of claims 1, 4, 5 or 6 wherein saidconductors are chosen from the group consisting of aluminum and copperconductors and said bonding material is softenable by the application ofheat.
 16. The method of claims 1, 4, 5 or 6 wherein said conductors arechosen from the group consisting of aluminum and copper conductors, andsaid bonding material is softenable by the application of solvent. 17.The method of claims 1, 4, 5 or 6 wherein said conductors are providedin a number greater than thirty-one and said bonding material issoftenable by the application of heat.
 18. The method of claims 1, 4, 5or 6 wherein said conductors are provided in a number greater thanthirty-one and said bonding material is softenable by the application ofsolvent.
 19. The method of claims 1, 4, 5 or 6 further comprising thestep of wrapping said ribbon with an elongated sheet of exteriorinsulation material and spooling the same for shipping, storage orhandling.
 20. The method of claims 1, 4, 5 or 6 further comprising thestep of wrapping said ribbon with an elongated sheet of exteriorinsulation material, and spooling the same for shipping, storage orhandling, and wherein said ribbon is spirally wrapped with said exteriorinsulation material.
 21. The method of claims 1, 4, 5 or 6 furthercomprising the step of wrapping said ribbon with an elongated sheet ofexterior insulation material, and spooling the same for shipping,storage or handling, and wherein said ribbon is longitudinally wrappedwith said exterior insulation material.
 22. The method of claim 1wherein said compressing and flattening steps are accomplishedsimultaneously.
 23. The method of claim 22 wherein said compressing andflattening steps are accomplished by differentially transporting saidconductors to compress said wires together in their direction oftransport and simultaneously flattening said helices transversely ofsaid mandrel axis and generally perpendicularly of said mandrelsurfaces.
 24. The method of claim 1 wherein said compressed andflattened and bonded helices define longitudinally extending ribboncable boundaries, said boundaries being rolled to define the exterioredges of said ribbon cable.
 25. The method of claim 5 wherein saidfolding steps are accomplished about a mandrel, said mandrel having twoopposite straight edges, the distance between said edges being greaterthan the transverse dimension of said edges.
 26. The method of claim 6wherein said folding steps are accomplished about a mandrel, saidmandrel having two opposite straight edges, the distance between saidedges being greater than the transverse dimension of said edges.
 27. Themethod of claim 5 or 6 wherein said mandrel is rotated as said foldingsteps are accomplished.
 28. The method of claim 5 or 6 wherein saidribbon cable is rotated as said folding steps are accomplished.
 29. Themethod of claims 1, 25 or 26 wherein the lateral dimension of saidmandrel is about equal to the number of conductors in said pluralitymultiplied by the outside diameter of said conductors divided by twicethe cosine of the acute angle between said conductor axes and thelongitudinal axis of said cable.
 30. The method of claim 4 wherein saidfirst and second conductors define two or more layers of conductorssuperimposed on each other.
 31. The method of claim 30 wherein each ofsaid layers is insulated from the other layers.
 32. The method of claim30 wherein the axis of said conductors of each of said layers isangularly disposed with the axis of said conductors of adjacent layers.